Vacuum type water absorption refrigerating system



1950 A. R. THOMAS 2,518,202

VACUUM TYPE WATER ABSORPTION REFRIGERATING SYSTEM Filed Oct. 25, 1944 4 Sheets-Sheet l ATTORNEY Aug. 8, 1950 A. R. THOMAS 2,518,202

VACUUM TYPE WATER ABSORPTION REFRIGERATING SYSTEM Filed Oct. 25, 1944 4 Sheets-Sheet 2 INV'7ENTOR @W -MW ATTORNEY Aug. 8, 1950 THOMAS 2,518,202

VACUUM TYPE WATER ABSORPTION REFRIGERATING SYSTEM Filed 061;. 25, 1944 4 Sheets-Sheet 3 J gm:

INVENTOR ,9 dam/am;

ATTORNEY 8, 1950 A. R. THOMAS 2,518,202

VACUUM TYPE WATER ABSORPTION REFRIGERATING SYSTEM Filed 001;. 25, 1944 4 Sheets-Sheet 4 NITED sun-:5, "PATENT oi-Pica 2,518,202

VACUUM TYPE WATER ABSORPTION REFRIGERATIN G SYSTEM Albert R; Thomas, deceased, late ofEvansvillc, Ind., by The National City Bank, administrator, Evansville, Ind., assignor to Serve], Inc., New York, N. Y., a corporation oi Delaware Application October 25, 1944, Serial No. 560,214

16 Claims. (Cl. 62-5) This invention relates to absorption type refrigeration systems utilizing water as refrigerant and operating under partial vacuum.

An object of the invention is to provide such a system utilizing as absorbent a water solution of a solid material such as lithium chloride. lithium bromide, or the like, and in which deposit of the solid material does not occur under any changes that may occur in operating conditions of the system. Another object is to pro- 'vide for liquid circulation and application of heat in a manner to aflord large refrigerating capacity with minimum size and amount of apparatus.

A vacuum type water absorption system has an evaporator, an absorber, and a still comprising a generator or boiler and a condenser. The system contains, by way of example, a water solution of lithium bromide. Heat is applied to the generator or boiler so that water vapor is expelled from the solution. The water vapor is liquefied in the condenser and the water is conducted to the evaporator. The pressure is lower in the evaporator so the water vaporizes therein at a temperature corresponding to the pressure. The resulting vapor passes to the absorber where it is absorbed into solution. The system is evacuated so that the vaporization can proceed at a temperature in the evaporator low enough, for instance, for cooling air for comfort purposes. The still operates at a higher pressure than the evaporator and absorber.

In accordance with the present invention, the boiler is formed of a number of riser tubes in a steam jacket and liquid being heated flows upward in these tubes by a vapor lift action commonly referred to as a climbing film action. A pump is provided to cause circulation of absorbent solution in a local circuit including the absorber. The boiler or generator is in abranch circuit through which solution is withdrawn from the local absorber circuit and returned thereto after expulsion of water vapor from the solution in the generator. Flow of liquid in the branch circuit is caused partly by pressure differential due to the pump in the absorber circuit and partly by gas lift action in the generator.

Associated with that part of the branch circuit which conducts solution from the generator back to the absorber circuit there is a device for sensing the concentration of the solution. The rate of application of heat to the generator is controlled by the sensing device so that the solution concentration is kept below saturation at temperatures encountered throughout the solution circuits.

In the drawings: Fig. 1 shows more or less diagrammatically a refrigeration system embodying the invention; Figs. 2 and 3 are enlarged views showing in more detail the structure of the concentration sensing device in Fig. 1; Fig. 4 is a diagram showing the electrical connections between the concentration sensing device and the generator heating control device in Fig. 1; Fig. 5 shows more or less diagrammatically a system like that shown in Fig. l but having a modified solution circuit; Fig. 6 is a view of part of' the system shown in Fig. 1 provided with a different arrangement for control of the generator heating by the concentration sensing device; and Fig. 7 is an enlarged view showing in more detail a portion of the control structure in Fig. 6.

Referring to Fig. l of the drawing, the system includes a combination generator and vaporliquid lift l0 comprising a shell or jacket I l within which are a number of riser tubes l2. The space I3 around the tubes [2 is closed at the upper end by a plate II; and at the lower end by a plate I5. The open ends of the tubes l2 project through the plates l4 and IS. The lower end of the shell H is closed by a plate l6 which is spaced from the tube plate 15 forming an inlet header space II. The upper end of the shell ll projects into the lower part of an enlarged header or separating vessel l8. Baflie plates is are positioned in the separator [8 above the upper ends of the generator tubes II. The lower part of the generator tube space I: is provided with a condensate drain 20.

A steam 'boiler 2| has one or more heating flues 22 into the lower end of which is projected a flame of a burner 23. The dome of the steam boiler 2| is connected by a pipe 24 to the jacket space I3 of the generator ID. A hand valve 25 and a controlled motor operated valve 26 are provided in the steam pipe 2|.

The hand valve 25 is normally left open. Steam flows from the boiler 2| through pipe 24 to the jacket space l3 of the generator Ill where it envelops the tubes l2 and heats these tubes to a maximum temperature of 212 F. because the upper end of the Jacket space 13 is open to atmosphere through a vent 21.

The enlarged header or separator 18 at the upper end of the generator [0 is connected by a pipe 28 to a water cooled condenser 29. This condenser comprises jacketed tubes 30 opening at one end in a header 3|, and at the other end in a header 32. The header 32 is divided into upper and lower halves by a partition 33. Cooling water enters the lower part of header 32 from trap 42.

connected by a pipe 43 to the top of the absorber .1 3 a pipe, 34, iflows through the lower bank of tubes,

v header 3|, and the upper bank of tubes to the upper part of header 3!, which it leaves through a pipe 35.

An evaporator tank 35 is located above an ab- 31. A manual valve 44 is connected in pipe 43. The bottom of the evaporator 35'has .a sump 45 connected by a pipe 45 to the intake of a water pump 41. The discharge of pump 41 is connected by a pipe 48 to the lower end of a cooling coil or cold radiator 49. The upper end oi coil 45 is connected by a conduit 50 to a spray head 5| in the upper part of the evaporator 35. v

A sump 52 in the bottom of the absorber 31 is connected by a pipe 53 to the intake of a solution pump 54. The discharge of pump 54 is connected by a pipe 55 to a spray head 55 in the upper part of the absorber 31. A cooling coil 51 is located in the absorber tank 31 below the spray head 55. The coil 51 has a number of sections joined at the bottom by a header 58 and at the top by a header 59. A pipe 50 provides an inlet connection for cooling water to header 55. The header 59 is connected by pipe 34 to the condenser 29 as previously described. The

bottom of the absorber 31 is connected to the separator III at the upper end of the generator by a pipe 5|. The pipe 5| projects upward within the header |8 and the open end of this pipe is surrounded by a baille plate 52. The pipe 5| forms a deep trap 53.

A liquid heat exchanger 54 has an outer liquid space 55 and an inner liquid space 55. Pipe 55 which is connected to the discharge of the solution pump 54 is also connected by a pipe 51, the inner space 55 of the liquid heat exchanger, and a pipe 58 to the bottom header H of the generator I W. The bottom of the generator upper header or separator 8 is connected by a pipe 59, a vessel 10, a pipe 1|, the outer passage 55 of the heat exchanger, and a pipe 12 to a discharge conduit 13 located in the upper part of the absorber 31.

The vessel contains a float 14. By also consulting Figs. 2 and 3 it will be seen that the float 14 is connected to a rod 15 which projects through an opening in the wall of vessel 10. The rod 15 is pivoted on a pin 15. This pivot permits the float to move up anddown. The opening through which the rod 15 projects through the casing 10 is sealed between the inside of the casing and the rod 15 by a resilient bellows 11. That part of the rod 15 which proiects outside of the casing 10 is provided with a hanger "on which may be placed any desired number of weights 18 to adjust the effective weight of the float 14.- The projecting end of the float rod 15 also carries an arm 50 comprising a movable contact arm for a rheostat 8|. Inside of vessel 10, pipe 1| projects upward to the top of the vessel, and a baffle plate 82 is located in front of the opening for pipe 59. The purpose is to reduce effect on the float of flow of solution entering through pipe 59 and leaving through pipe 1|.

The refrigerating system is charged with, by way of example, :a water solution of lithium bromide. The refrigerating system is evacuated and kept evacuated during operation. The application or heat, as previouslyflescribemto the generator tubes l2 cause expulsion of water vapor from solution in these tubes. The water vapor flows upward in the tubes l2 and causes 8011b;- tion to likewise flow upward in these tubes. Adjacent the lower ends of the tubes the action is similar to that or an air lift or vapor bubble pump. 1115118 upper regions of the: tubes, there is van increasingly larger core of'vapor rising in the center of the tube and dragging upward on the inner surfaces of the tubes a fllm of liquid.

The vapor and liquid issue from the upper ends of the tubes I! into the separator l5.

Vapor flows from the separator |5 through pipe to the condenser 23. The condenser 29 performs the function or liquetying the vapor by condensation thereof on the tubes 30 which are cooled by water flowing through the condenser. The condensate, water, flows from the condenser through pipe into the evaporator 35. The deep trap 42 in the pipe 40 provides for maintaining a column of water to balance the diflference in pressures in the evaporator and condenser.

Water is circulated from the evaporator 35 through pipe 45, pump 41, cooling coil 49, and pipe back to the spray head 5| in the upper part of the evaporator. Water sprayed in the evaporator vaporizes to produce a cooling eflect. The low pressure for causing this vaporization to take place at a low temperature is maintained by operation of the absorber. The vapor formed in the evaporator 35 flows through the pipe 35 into the absorber. The vapor is here absorbed into the solution and the heat of absorption is removed by transfer to cooling water flowing in the coils 51. Absorption liquid is drawn from the absorber sump 52 and flows through pipe. 53. pump 54, and pipe 55 to the spray head 55- 51, liquid heat exchanger 54, and pipe 55 to the inlet header H of the generator I5. Absorption liquid from which water vapor has been expelled flows from the separator |5at the upper end of the generator l5 through the pipe 59, the concentration control vessel .15; pipe 1| liquid heat exchanger 54, and pipe 12 to the spray head 13 in the upper part 01 the absorber 31. The removal of water vapor from the absorption solution in this branch of the circuit maintains the desired concentration of solution'in the absorber.

The previously described gas lift action in the generator It causes. circulation of absorption liquid in this branch of the circuit at a rate which varies with the heating of the generator.

Pipe 5| provides an overflow from the separator It to the absorber 31. The deep trap 53 in conduit 5| accommodates a liquid column to balance the difierence in pressures in the generator and absorber.

When the concentration of absorption liquid flowing through vessel 10 is at the desired value, the float 14 stands in a position such that the contact lever is at the center of the rheostat 5|. float to this position. If the solution in vessel 15 becomes lighter, the float sinks. If the solution in vessel 10 becomes heavier, the float rises.

Movement of the float 14 causes the contact arm 50 to move one way or the other from the center The resilience of the bellows 11 urges the spray head 56.

of resistance. M. This causes the steam valve26 tobe operated. When the floatrises. the valve abrasion 26 is operated to decrease-the supply of steam to the generator I so that less water vapor will be expelled from solution in the generator.

, windingas. When winding a4 is energized the motor revolves in one direction and when the winding 85 is energized the motor revolves in the opposite direction. A second rheostat 86 is identical with the rheostatBI and has a. contact, arm 01 moved by rotation of the valve operating shaft 03. The rheostats 8| and 86 are connected in a symmetrical circuit of which one branch includes a relay coil 08, and the other branch includes a relay coil 89. One side o f, a source of electrical energy 90 is connected to .the rheostat arm 80 and theother side is connected to the rheostat-arm 81. When these arms are in the centers of the rheostats BI and 86 the symmetrical circuits are balanced and the armature SI of the balancing relay is neutral. The armature 9| operates a single pole double throw switch 92 for connecting one side of the electrical source 90 to either the motor winding 84 or the winding 85. When the float I4 moves the rheostat arm 00 one way or the other, the circuits are temporarily unbalanced, and one winding of the balancing relay overcomes the other to operate the switch 92 to start the motor which operates the like parts in these figures are indicated by the same reference numerals.

In the system of Fig. 5, the source of steam for heating the generator I0 has been omitted, and the concentration control device has also been omitted, with the understanding that both would be provided in this system in the manner previously described in connection with Fig. l, The absorber sump 52 is connectedpy-a' pipe 93 to a vessel 94 containing a centrifugal pump 95. Electric motor 96, located above the liquid level in vessel 94 is connected by a vertical drive shaft 91 to the pump 95. The motor 96 is mounted on top of the vessel 94, and the drive shaft 9'I projects downward into vessel 94. The drive shaft 91 is provided with a labyrinth 98 at the top of vessel 94 to prevent splashing of liquid into the motor chamber. The motor 96 is located within a casing 99 which is sealed to the pump vessel 94.

The pump 95 is connected by a discharge pipe I00 to a purge chamber IOI. A pipe I02 connects the purge chamber IOI to the absorber The pipe 61 connects th purge chamber to the liquid heat exchanger 64. The purge chamber IN is provided with a vent I03 controlled by a valve I04. purge chamber operates valve IM.

A pipe I06 has one end I0! open in the lower part of the absorber tank 31, and the other end I00 open in the intake of the centrifugal pump 95. During operation of the system in the manner previously described in connection with Fig.

1- 6 1, solution from the absorber sump 52 flows through pipe 93 into the pump vessel 94. The

pump 35 is submerged in liquid in vessel 94 and pumps this liquid through pipe I00 into the purge chamber IOI-. Liquid. flows from chamber IOI through the pipe I02 to the absorber spray head 56. Some liquid also flows from the purge chamber through pipe 61, liquid heat exchanger 64, and pipe 68 to the generator inlet header I1.

Non-condensible gases entering or formed in the still section of the system are swept by vapor flow to the outlet end of the condenser 29-. From thence such gases are carried by condensate flowing from the condenser through pipe 40 into the evaporator .36. The gases are. trapped by liquid entering the condenser end of pipe 40 due to the provision of the shallow trap or syphon 4|. trapped gases are carried by the flow of liquid through pipe 40 into 'the evaporator 36. Noncondensible gases in the evaporator 36 and absorber 31 are swept by vapor flow to the lower part of absorber 31 from whence the gases are A float I05 in the drawn through pipe I06 into the liquid entering the intake of the pump 95. The gas flows with the liquid from the pump through pipe I00 to the purge chamber IOI. The gas accumulates in the upper part of the chamber IM and when the accumulation is sufllcient, the surfac level of liquid in the chamber IOI is depressed to such an extent that the float I05 lowers the valve I04 to permit the gas to escape through the vent I03. To cause removal of gas from the purge chamber I 0|, a vacuum pump may be connected to the vent I03 and controlled so that the vacuum pump operates when the purge valve I04 is open.

In Fig. 6 is shown a part of the system illustrated in Fig. 1, provided with a modified form of concentration control. In this modification, the boiler heating burner 23 is controlled to vary the supply of steam to the generator I0. A pressure operated valve IDS is connected in the fuel line to the burner 23. The pressure chamber H0 of this valve is connected by a pipe III to a bleed valve H2. The bleed valve is operated by a rod 'Il3 which projects through the top of a vertical float vessel II4. A bellows H5 provides a seal between the float vessel H4 and the rod II3. A float H6 is fastened on the valve operating rod II3 within the float vessel H4. The separator I8 is connected by a pipe 69 to the float vessel H4, and the float vessel is connected by a pipe 1| to the liquid heat exchanger 64 so that the float vessel II4 contains liquid in its path of flow from the generator I0 toward the absorber.

Pipe III is connected by a pipe III to a suitable source of fluid under pressure such as compressed air. The pressure of fluid exerted in valve chamber III) is varied by the amount of opening of the bleed valve H2. When the concentration of solution in the float vessel H4 is at the desired value, the bleed valve opening is such that the boiler heater 23 supplies the desired amount of heat. Upon increase or decrease in concentration of solution in the float vessel II4, the bleed valve H2 is operated by the float 6 to change the heat input to the boiler 2i accordingly.- Various changes and modifications may be made within the scope of the invention asset forth in the following claims.

. What is claimed is:

1. An absorption refrigeration rystem having an absorber, a generator comprising a vapor liquid lift, a heat exchanger, a vapor liquefier,

The

pump for causing now in said branch, said 'hquefier and said evaporator being connected in a refrigerant course between said generator and'absorber.

a modulating valve for regulating the supply of heatingm'edium to said generator, and a de- 2. An absorption refrigeration system having an absorption liquid circuit including an absorber and a pump'connected to receive liquid from the absorber and pump it back through the absorber, a heat exchanger, a vapor liquid lift connected by means including said heat exchanger to receive liquid from said circuit and de.iver liquid to said absorber, a liquefier' connected to,receive vapor from said hit, and an evaporator connected to receive liquid from said liquefler and deliver vapor to said absorber.

3. An absorption refrigeration system having a circuit for absorption liquid, a chamber forming a gas trap in said circuit, a vent from said chamber, and a device for opening and closing said vent responsive to accumulation of gas trapped in said chamber without disturbing flow 'of liquid in said circuit.

4. A system as set forth inclaim 3 in which said device is a valve operated by a float in said chamber.

5. An absorption refrigeration system having a generator, a heater for heating said generator, an absorber, a circuit for absorption liquid including said absorber and a pump for causing circulation of liquid therein, and a branch circuit including said generator connected to receive liquid from and return it to said absorber circuit, said generator comprising a heat-operated liquid circulator to vary the rate of flow of liquid in said branch in accordance with heating thereof.

6. An absorption refrigeration system having a generator, a heater for heating said generator, an absorber, a circuit for absorption liquid including said absorber and a pump for causing circulation of liquid therein, a branch circuit including said generator connected to receive liquid from and return it to said absorber circuit, said generator comprising a heat-operated liquid circulator to vary the rate of flow of liquid in said branch in accordance with heating thereof, and a device operative responsive to concentration of the absorption liquid to control the heating of said generator.

7. In an absorption refrigeration system hav-v ing a plurality of interconnected elements to provide a closed circuit for circulating a refrigerant and absorption solution, a generator in said circuit having upright tubes forming vertical heating surfaces for expelling refrigerant vapor from the absorption solution and raising solution by vapor lift action, means for heating the generator tubes, and a device responsive to the specific gravity of the absorption solution for controlling the vertical extent to which said generator tubes are heated to maintain the concentration of the solution within predetermined limits.

8. In an absorption refrigeration system having a plurality of interconnected elements to provide a closed circuit for circulating a reirigc-rant and absorption solution, a generator in said circuit having upright tubes forming vertical heating surfaces for expelling refrigerant vapor from the absorption solution and raisin the solution by vapor lift action, means" for supplying heating medium to heat the generator tubes,

vice responsive to the specinc gravity of the ab- "sorption solution for adjusting the valve in accordance with variations in the concentration of ti'ie'absorption'solution whereby to maintain the concentration within predetermined limits:

' 9. in an absorption refrigeration system having a plurality of interconnected elements to provide a closed circuit for circulating a re- Iri erant and absorption solution, a generator in said circuit for'expelling refrigerant vapor from 1 the absorption solution, means for supplying steam to heat said generator, a modulating valve 101' controlling the flow of steam to said generator, and a float responsive to the specific gravity of the absorption solution flowing from the generator for adjusting the modulating valve in accordance with the concentration of the solution whereby to maintain the concentration within predetermined limits.

10. In an absorption refrigeration system having a plurality of interconnected elements to provide a closed circuit for circulating a refrigerant and absorption solution, a generator in said circuit for expelling refrigerant vapor from the absorption solution, means for heating the generator, a modulating valve for regulating the heating of said generator, an electric motor for adjusting said valve, and a float responsive to the specific gravity of the absorption solution flowing from the generator for controlling the operation of said motor in accordance with variations in the concentration of the absorption solution whereby to .maintain the concentration within predetermined limits.

11. In an absorption refrigeration system having a plurality of interconnected elements to provide a closed circuit for circulating a refrigerant and absorption solution, a generator in said circuit for expelling refrigerant vapor from the absorption solutio means for heating said generator, a modulating valve for regulating the heating of said generator; an electric motor for adjusting said valve, an electric circuit for said motor including a resistance, and a movable member responsive to the specific gravity of the absorption solution, said movable member varying the resistance of the electric circuit to adjust said valve in accordance with variations in the concentration of the absorption solution whereby to maintain the concentration within predetermined limits.

12. In an absorption refrigeration system having a plurality of interconnected elements to provide a closed circuit for circulating a refrigerant and absorption solution, a generator in said circuit for expelling refrigerant vapor from the absorption solution, means for heating said generator, a modulating valve for regulating the heating of said generator, an electric motor for adjusting said valve, an electric circuit for said motor including a resistance, a chamber connected in said system for receiving concentrated absorption solution from the generator, and a float in said chamber responsive to the specific gravity of the absorption solution, said float having a movable arm for varying the resistance of the electric circuit to adjust said valve in accordance with variations in the concentration of said absorption solution whereby to maintain concentration within predetermined limits.

13. In an absorption refrigeration'system having a plurality of interconnected elements to provide a closed circuit for circulating a refrigerant and an absorption solution, a generator in said circuit, means for heating said generator to expell refrigerant vapor from the absorption solution, a valve for controlling the heating of said generator, an electro-magnetic device for adjusting the valve to vary the heating of said generator, a rheostat connected to said device, and a sensing element in said circuit responsive to the concentration of the absorption solution and connected to operate the rheostat and thereby actuate the valve to adjust the operation of the generator in accordance with the condition of the absorption solution.

14. In an absorption refrigeration system having a plurality of interconnected elements to provide a closed circuit for circulating a refrigerant and an absorption solution, a generator in said circuit, means for supplying steam to said generator to heat the absorption solution and expell refrigerant vapor therefrom, an adjustable valve for controlling the flow of steam to said generator, and a float in the circuit responsive to the concentration of the absorption solution flowing from the generator and connected to adjust the valve whereby to increase -or deand evaporator, means for heating the liquid circulator, a device in the absorption liquid circuit responsive to the concentration of the liquid therein to control the rate of heating of said liquid circulator, a chamber in the absorption liquid circuit forming a gas trap, a vent from said chamber, and a device for opening and closing said vent responsive to accumulation of gas trapped in said chamber.

16. An absorption refrigeration system having an absorber connected in a first circuit for absorption liquid including an unheated liquid circulator, said absorber also being connected in a second circuit for absorption liquid including a heat exchanger and a heated liquid circulator, and'acourse for refrigerant from said heated circulator to said absorber including a liquefler and-evaporator.

THE NATIONAL CITY BANK. Adminis rator of the Deceased,

By JOHN N. EWING,

Vice President.

REFERENCES CITED The following references are of record in th tile of this patent:

UNITED STATES PATENTS Roswell Sept. 18, 1945 Estate of Albert R. Thomas, E 

